JPS62204905A - Reactive injection molding method - Google Patents

Abstract

PURPOSE:To obtain a molded form substantially no bubble and prominent in physical properties, such as tensile strength, elongation at rupture and the like, as well as in appearance, by a method wherein a mixing head, injecting material upward, is arranged to effect reactive injection molding. CONSTITUTION:A mold 2 has a cavity 1 and is equipped with a material passageway 3. The injection port 4a of a mixing head 4 is arranged vertically so that material is injected upward. An auxiliary mold 5 contains an auxiliary material passageway 5a for guiding the material, injected from the mixing head 4, into the material passageway 3 of the mold 2 and is arranged between the mixing head 4 and the mold 2 so that one end of the auxiliary material passageway 5a communicates with the material passageway 3 of the mold 2 while the other end of the same communicates with the injection port 4a of the mixing head 4. According to this reactive injection molding method, a molded form, including substantially no bubble and prominent in physical properties, such as tensile strength, elongation at rupture or the like, as well as in appearance may be obtained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a reaction injection molding method, and the method of the present invention is applicable to reaction injection molding of nylon, unsaturated polyester, epoxy resin, cyclopentadiene, polyurethane, etc. It can be applied to any molding method, and is particularly suitable for manufacturing nylon molded products by reaction injection molding using ω-lactam as a raw material.

[Conventional technology]

A method of directly obtaining molded products such as nylon, unsaturated polyester, epoxy resin, cyclopentadiene, and polyurethane by injecting a highly reactive liquid raw material into a mold and performing polymerization and molding within the mold, so-called reaction injection. Molding methods have been attracting attention in recent years.

In this reaction injection molding method, two or more types of highly reactive liquid raw materials are collidingly mixed in a mixing paddle 4 arranged parallel to the mating surface 6 of the mold 2 as shown in FIG. After that, it is injected into the mold 2.

(Problems to be Solved by the Invention) In the conventional reaction injection molding method described above, when the liquid raw materials are collided and mixed, the air or inert gas present in the mixing head is injected into the liquid raw materials as bubbles. , air bubbles are likely to be contained inside the molded product obtained. Therefore, the molded product obtained has many air bubbles over almost the entire surface of one side (back side), and physical properties such as tensile strength and elongation at break, as well as appearance This phenomenon is noticeable in the reaction injection molding process for nylon, which uses a low-viscosity ω-lactam as a liquid raw material.

[Means for solving problems]

As a result of various studies aimed at solving the above-mentioned problems, the present inventors have determined that the mixing head 4 is arranged so that the raw material is injected upward, as shown in FIG. It has been found that by molding, a molded product with almost no bubbles, good physical properties such as tensile strength and elongation at break, and an excellent appearance can be obtained.

The present invention has been made based on the above knowledge, and involves colliding and mixing a small amount (both two types of highly reactive liquid raw materials) in a mixing head, injecting the mixture into a mold having a cavity corresponding to the shape of the molded product, and reacting. The molding method is characterized in that the mixing head is arranged so that the raw material is injected upward, and the raw material injected from the mixing head is injected into the mold via a raw material auxiliary passage. A reaction injection molding method is provided.

The reaction injection molding method of the present invention will be explained below with reference to the drawings.

FIG. 1 schematically shows a preferred example of the connection relationship between the mixing head and the mold in the apparatus used for carrying out the reaction injection molding method of the present invention.
2 is a mold having an 8-cavity cavity 1; 3 is a raw material passage provided in the mold 2; 4 is a mixing head with an injection port 4a thereof. The injection port 4a is arranged vertically so that the raw material is injected upward. 5 is
The auxiliary mold has a raw material auxiliary passage 5a inside for guiding the raw material injected from the mixing head 4 to the raw material passage 3 of the mold 2, and the auxiliary mold 5 has one end of the raw material auxiliary passage 5a. The mixing head 4 and the mold 2 are connected so that one end thereof communicates with the raw material passage 3 of the mold 2 and the other end thereof communicates with the injection port 4a of the mixing head 4.
is located between. 6 is a mating surface of the mold 2.

Although FIG. 1 shows an example in which the raw material auxiliary passage 6 is provided within the auxiliary mold 5, the raw material auxiliary passage 6 may be integrated into the mold 2. Further, the mixing head 4 may be arranged so that the raw material is injected upward from the injection port 4a, and depending on the shape of the mold 2, the type of liquid raw material, etc., the mixing head 4 may be arranged within a range that does not impair the object of the present invention. The direction of the injection port 4a of the mixing head 4 may be tilted as appropriate.

Further, as an apparatus used for implementing the reaction injection molding method of the present invention, a mixing head is arranged so that the raw material is injected upward, and the raw material injected upward from the mixing head is guided to the mold. The apparatus used in the conventional reaction injection molding method can be used as is, except for using an auxiliary mold having a raw material auxiliary passage or a mold provided with a raw material auxiliary passage.

Therefore, when implementing the reaction injection molding method of the present invention,
The feeding of two or more highly reactive liquid raw materials to the mixing head, collision mixing within the mixing head, polymerization and molding of the mixed liquid filled in the cavity, and removal of the molded product are the same as in the conventional method. The highly reactive liquid raw materials that have been collision-mixed in the mixing head are injected upward from the injection port of the mixing head and guided into the cavity of the mold via the raw material auxiliary passage.

As a result, according to the reaction injection molding method of the present invention, it is possible to obtain a molded article that is substantially free of bubbles, has good physical properties such as tensile strength and elongation at break, and has an excellent appearance.

Next, as a representative example of the reaction injection molding method of the present invention, a case where the present invention is applied to a method of manufacturing a nylon molded article using ω-lactam as a highly reactive liquid raw material will be described.

Specific examples of ω-lactam, which is a highly reactive liquid raw material, include T-butyrolactam, δ-valerolactam, δ-caprolactam, ω-enantholactam, ω-capryllactam, ω-undecanolactam, ω-laurinlactam, etc. can be mentioned. These ω-lactams may be used alone or in combination of two or more.

All alkali catalysts used in known alkaline polymerization methods of ω-lactams can be added to the ω-lactam, and specific examples of such alkali catalysts include:
Alkali metals, alkaline earth metals, their hydrides,
Oxides, hydroxides, carbonates, alkylates, alkoxides, Grignard compounds, sodium naphcrene, and also reaction products of the above metals or metal compounds with ω-lactams, such as sodium salts of ω-lactams, potassium Salt is an example. The amount of the alkali catalyst added is preferably 0.05 to 10 mol%, particularly 0.2 to 5 mol%, based on the ω-lactam.

In addition, all cocatalysts used in known alkaline polymerization methods can be added to the ω-lactam,
Specific examples of such promoters include N-acyllactam,
Mention may be made of organic isocyanates, acid chlorides, acid anhydrides, ester urea derivatives, carbodiimides, ketenes. The amount of the co-catalyst added is 0 to ω-lactam.
．． It is preferably 0.01 to 5 mol%.

Further, a reaction product of the above-mentioned co-catalyst and a polyol, polyamine or polycarboxylic acid, which has a co-catalytic effect, can also be used as a co-catalyst. Specific examples of these compounds include hexamethylene diisocyanate,
4,4′-diphenylmethane diisocyanate and polyethylene glycol,
Polyols such as polypropylene glycol, polytetramethylene glycol, polyester glycol, poly (ε-caprolactone) diol or polyamines such as polyoxyethylene diamine, polyoxypropylene diamine, polyamide whose terminal group is an amino group, or polyethylene oxydiglycolic acid , a reaction product with polybujenyafoliamide whose terminal group is a carboxylic acid,
Acyl lactams such as adiboyl biscaprolactam, terephthaloyl biscabrolactam, or hexamethylene-1,6-biscarbamide caprolactam, N
-Phenyl-No-isopropyl-p-phenylenebiscarbamide A reaction product of a carbamide lactam such as caprolactam and the above-mentioned polyol or polyamine can be mentioned. When these reaction products are used as cocatalysts, the amount added is 1 to 6 to ω-lactam.
Preferably it is 0% by weight.

The polymerization of the ω-lactam is preferably carried out at a temperature higher than the melting point of the ω-lactam and lower than the melting point of the resulting polyamide.

In the present invention, the ω-lactam can also be polymerized in the presence of stabilizers such as plasticizers, fillers, fibers, blowing agents, dyes, pigments, and antioxidants that do not substantially inhibit the polymerization reaction. Specific examples of preferred plasticizers include N-alkylpyrrolidone and dialkylimidazolidinone, which can be used in an amount of 2 to 25% by weight based on the ω-lactam. Specific examples of the filler include calcium carbonate, wollastonite, kaolin, graphite, gypsum, feldspar, mica, asbestos, carbon blank, and molybdenum disulfide. Specific examples of the fiber include milled glass. Examples include glass fibers such as (crushed glass), graphite fibers, fibrous magnesium compounds, potassium titanate fibers, mineral fibers, boron fibers, and steel fibers. These fillers and fibers can be used in a proportion of 2 to 50% by weight, based on the ω-lactam. Further, as the above-mentioned blowing agent, benzene, toluene, xylene, etc. are suitable, and can be used in a weight ratio of 1 to 15% by weight relative to the ω-lactam.

〔Example〕

EXAMPLES Below, the present invention will be explained in more detail by giving examples and comparative examples of the present invention. In the embodiment, as shown in FIG. 1, the mixing head is arranged so that the raw material is injected upward, and the liquid raw material injected upward from the mixing head is injected into the mold. An auxiliary mold having an auxiliary passage was installed between the mixing head and the mold, and in a comparative example, the mixing head was arranged parallel to the mating surface of the mold as shown in Fig. 2. carried out.

Example 1 4 kg of substantially anhydrous ε-caprolactam and 4 kg of sodium caprolactam were placed in a component A tank of a nylon RIM molding device, and the temperature was maintained at 100°C.

In addition, the B component tank contained substantially anhydrous ε-caprolactam 2.4 k+r, hexamethylene-1,6-biscarbamide caprolactam 494 g, and diefermine D 2
000 (manufactured by Mitsui Texaco Chemical ■) 1.6 kg and milled glass fiber (manufactured by Centsil Glass 01, E
FII-100-31) Add 1.6 kg and 100
Mix uniformly at ℃.

The A component and the daily component were supplied to a mixing head at a volume ratio of 1:1 and mixed by collision at a pressure of about 15 kg/-.
Cavity internal volume heated to 0℃: 280cc
(k13501m5. Width 200mm, height 401111
It was injected into a box-shaped mold with a diameter of 2.5 m + w). One minute after injection, the mold was opened and the molded product was taken out.

The surface of the molded product obtained was smooth and free of bubbles.

Example 2 Instead of a box-type mold, the cavity internal volume was 300cc (vertical 3
A molded product was obtained by repeating the same method as in Example 1, except that a plate-shaped mold of 50 mm x 350 InIm wide x 2.5 mm wide was used.

The surface of the molded product obtained was smooth and free of bubbles.

Example 3 ATBN instead of Diefamine D 2000 as component B
A molded article was obtained by repeating the same method as in Example 1 except for using a 1300 x 16 mold (manufactured by Ube Industries).

The surface of the molded product obtained was smooth and free of bubbles.

Example 4 ATBN instead of Diefamine D 2000 as component B
1300 x 16 (manufactured by Ube Industries Association) was used, and the internal cavity volume was 300 cc (vertical 350 cc) instead of a box mold.
A molded article was obtained by repeating the same method as in Example 1, except that a plate-shaped mold having dimensions of III11×width 3501111×2.5+1111 was used.

The surface of the molded product obtained was smooth and free of bubbles.

Example 5 Substantially anhydrous ε-caprolactam 2.8k in 8-component bath
tr, 370 g of hexamethylene-1,6-biscarbamide caprolactam and ATBN 1300 X16.

(manufactured by Ube Industries, Ltd.) A molded article was obtained by repeating the same method as in Example 1 except that 1.2 was added.

The surface of the molded product obtained was smooth and free of bubbles.

Comparative Example 1 A molded article was obtained by repeating the same method as in Example 1 except that the mixing head was arranged horizontally as shown in FIG.

One side of the obtained molded product [the back surface of the molded product (the part of the molded product corresponding to the upper side 1a of the cavity 1 shown in FIG. 2)] has a diameter of 0.5 to 11 over the entire surface. Many air bubbles were present.

Comparative Example 2 A molded product was obtained by repeating the same method as in Example 2, except that the mixing head was arranged horizontally as shown in FIG.

On one side (back side) of the obtained molded article, many air bubbles with a diameter of 0.5 to lIw11 were present over the entire surface.

Comparative Example 3 A molded product was obtained by repeating the same method as in Example 3 except that the mixing head was arranged horizontally as shown in FIG.

A large number of air bubbles having a diameter of 0.5 to 111ffi were present over the entire surface of one surface (back surface) of the obtained molded product.

Comparative Example 4 A molded article was obtained by repeating the same method as in Example 4 except that the mixing head was arranged horizontally as shown in FIG.

A large number of bubbles with a diameter of 0.5 to 1 cm were present over the entire surface of one surface (back surface) of the obtained molded product.

Comparative Example 5 A molded article was obtained by repeating the same method as in Example 5, except that the mixing head was arranged horizontally as shown in FIG.

A large number of bubbles with a diameter of 0.5 to 11 were present over the entire surface of one surface (back surface) of the obtained molded product.

〔Effect of the invention〕

According to the reaction injection molding method of the present invention, it is possible to obtain a molded article that is substantially free of bubbles, has good physical properties such as tensile strength and elongation at break, and has an excellent appearance.

The reaction injection molding method of the present invention can be applied to reaction injection molding methods for nylon, unsaturated polyester, epoxy resin, cyclopentadiene, polyurethane, etc. In particular, using ω-lactam as a liquid raw material, reaction injection molding This method is extremely suitable for manufacturing nylon molded products.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a preferred example of the connection relationship between a mixing head and a mold in an apparatus used for carrying out the reaction injection molding method of the present invention, and FIG. FIG. 2 is a schematic diagram of the connection relationship between the mixing head and the mold in the apparatus.

Claims (1)

[Claims] In a reaction molding method in which at least two types of highly reactive liquid raw materials are collided and mixed in a mixing head and injected into a mold having a cavity corresponding to the shape of the molded product, the raw materials are injected upward. A reaction injection molding method characterized in that the mixing head is arranged in such a manner that the raw material injected from the mixing head is injected into the mold through a raw material auxiliary passage.